Resumen
At present time and for several years, some different concretes have been developed for special purpase. The most used procedure is to modify the cementbased matrix, to improve some properties, subtitrating components or using admixtures, additions or both. Among these special concretes is the concretewith fibers, that according to ACI 544-3R-84: " fiber reinforced concrete is a composite material made of hydraulic cements, fine and gross aggregate, anda dispersion of discontinuos, small fibres". This paper analyzes the influence of the type and percentage of glass fiber, on the concrete physical mecanicproperties. For this differents mixes were made changing the type and percentage of glass fiber added. The results are compared with those of a standardmix. The physical mechanical properties as workability, plastic cracking, toughness, abrasion and impact resistance.